Try Q2 Weighting from Charlotte

Try running with the weighting method from Charlotte Van Hulse:

> Hello Chris,
>
> Later than I wanted, but here how I weight my events:
>
> I use as lumi values Ltotlow to normalise my events with 1100 GeV2.
> Here below how I obtain these values:
>
> Ltot=(Ntot[0]/nEv18_275)*L18_275;
> Ltotlow=(Ntot[1]/nEv18_275lowq2)*L18_275lowq2+Ltot;
> Ltothigh=(Ntot[2]/nEv18_275highq2)*L18_275highq2+Ltot;
>
> With Ntot[i]=total number of generated events, so entries in the trees.
> Here, i=0 is for the files that cover Q2>1 GeV2; i=1 is for 1100 GeV2.
>
> nEv18_275* are the total number of trials, which for the total sample at 18x275 GeV2 used for ecce were:
> nEv18_275=20000000;
> nEv18_275lowq2=20000000;
> nEv18_275highq2=4000000;
>
> The values L18_275* are the total MC luminosities, which I think Ralf provided you:
> L18_275=22.650255;
> L18_275lowq2=22.736391;
> L18_275highq2=1293.659173;
>
> I obtain them as follows:
> TObjString* crossSection=(TObjString*)f->Get("crossSection");
> TObjString* nEvents=(TObjString*)f->Get("nEvents");
> Lumi+=(nEvents->GetString().Atof()/crossSection->GetString().Atof());
>
> I then scale this Lumi as Lumi/=1e6 to obtain it in pb^-1.
> (The nEvents correspond to the nEv18_275*)
>
> More explanation about this is given here:
> [https://wiki.bnl.gov/eic/index.php?title=Simulations](https://urldefense.proofpoint.com/v2/url?u=https-3A__wiki.bnl.gov_eic_index.php-3Ftitle-3DSimulations&d=DwMFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=0UzrOYhLMv6dSHaDG4t4Bg&m=cMfGj8KuRGwpKxru9Rv4RRHzD_bP9xPob91KgpZsYfIun73savleQ_06R-mNnbx1&s=FdgTh7ADCKz1Hs60P78R5xzPFiuQ4JqetSJRnVBeimI&e=)
> in the section "MC Analysis Techniques".
>
> I hope all is clear. Otherwise, please do not hesitate to ask.
>
> greetings,
>
> Charlotte